1. Field of the Invention
The present invention relates to an improved power washer wand and, more particularly, to a power washer wand having a configuration that greatly reduces the back pressure exerted on the user.
2. Discussion of Related Art
Power washing, or pressure washing, is commonly used in the maintenance of buildings and other exterior surfaces. Power washing is typically performed using a device such as is seen in FIG. 1. A power washing machine 100 typically includes a pump 107 connected to a water source 109, and a wand 111 which is connected to the pump 107 by a hose 113. The power washer user holds the power washer wand 111 and activates a trigger 115 to expel from a nozzle or tip 117 a highly pressurized water stream against a surface. This highly pressurized water stream is typically used to remove dirt, mildew, and other unwanted substances from a surface.
One well-known drawback of power washing is the back pressure exerted from the highly pressurized water stream to the user. This back pressure has several drawbacks.
A first drawback is that the back pressure prevents the user from standing on the ground and extending his arms to reach high or distant surfaces. The pressure exerted from the surface and through the wand increases exponentially as it extends down a straight line. If a user extends his arm to wash a distant surface, the force from the water against the surface to the user's shoulder is much greater than, for example, the force from the surface to the user's elbow. Note that the pressure of the water stream against the surface may exceed 2000 lb/in2 and the distance from the surface to the user's shoulder (i.e., with arm extended) may exceed 6 feet. Thus, the pressure exerted on the user's shoulder may be great. Consequently, the user may need to erect a scaffold or ladder from which distant surfaces may be reached without the user extending his arm. This is inconvenient, time consuming, and expensive especially if a ladder or scaffold is not readily available. Moreover, this is dangerous. The back pressure exerted by the water stream may cause the user to fall from the ladder or scaffold. In some cases, some surfaces may not be reached even if a ladder or scaffold is used.
A second drawback is that the back pressure limits the size of the wand. Because the straight length from the surface through a straight line exponentially increases the force on the user, a long wand is difficult to operate. Thus, a wand for use with a high pressure nozzle cannot be made longer than several feet because the pressure from the surface being power washed to the user's elbow (or even to the trigger) is too great for convenient and safe use. Similarly, a wand for use with a high pressure nozzle cannot be connected to an extension, again because the forces on the user holding the proximal end of the wand/extension combination are too great.
As shown in FIG. 1, a typical wand 111 is connected to the hose 113 using a conventional “quick coupler” 119. If an extended wand was constructed of a number of portions connected using only conventional quick couplings, the extension would not be safe. This is because the back pressure exerted on the couplings would greatly stress the couplings and could result in the extension breaking during use. This effect make the power washer unwieldy and not easily maneuverable. This results in an inadequate washing of the distant surfaces. Another known wand is a telescopic wand. However, telescopic wands are intended for use only with low pressure nozzles. For example, a low pressure nozzle may have a 25° “fan out.” As seen in FIG. 2A, a tip 117′ having a large “fan out” distributes the water W along a large area of the surface being cleaned. As a result, the pressure against the surface is reduced. At the same time, the effectiveness of the power washer to remove unwanted substances from the surface is also reduced. On the other hand, as seen in FIG. 2B, nozzles having little or no “fan out,” such as a 0° nozzle 117″, focus all of the water stream's pressure on a small area of the surface being cleaned and thus are more effective at removing unwanted substances from the surface. For the reasons described above, however, a telescopic wand cannot be used practically with a high pressure nozzle.
A third drawback is that the back pressure tends to fatigue the user because the user exerts energy against this back pressure in order to hold the wand 111 steady during use.
U.S. Pat. No. 6,158,677, invented by the present inventor, discloses a power washer wand, one embodiment of which is shown in FIGS. 3A and 3B. In the embodiment shown in FIGS. 3A and 3B, a power washer wand 320 has a quick coupling 322 which detachably connects the wand to a hose 324. The embodiment of the power washer wand 320 shown in FIG. 3A also has a trigger 326 of the conventional type. Located between the trigger 326 and the nozzle or tip 328 of this wand is a loop or helix 330. Preferably, the loop 330 is located at a position which is slightly proximal from the nozzle, such as between several inches to a foot behind the nozzle 328.
The loop 330 preferably has a turn which brings the water stream back over itself. Most preferably, the turn is 270°. To reduce any problems in handling the power washer wand, it is preferable to reduce the diameter of the loop to be as small as possible. Due to current limitations in the fabrication process, the diameter of the loop in a commercial embodiment is approximately 3 inches. The inventor believes that this loop 330 balances the vector forces caused by the pressurized water stream against the surface being power washed.
Referring to FIG. 3A, the wand may optionally be provided with a standard swivel joint 332 (referred to as a universal joint in the previous applications). In the embodiment illustrated in FIG. 3A, the swivel joint 332 is located proximal to the nozzle 328 and distal to the loop 330. The standard swivel joint is a well-known coupling that connects two elements, in this case pipes, allowing freedom of movement in at least one plane. This swivel joint 332 therefore permits the wand nozzle 328 to be adjusted to a desired angle. The movement of the nozzle is illustrated by the dashed lines in FIG. 3A. It was found that during use of the inventive wand, if the angle between the wand nozzle 328 and the surface being washed fell outside of a desired range of angles between about 0° and 45° with respect to horizontal, the back pressure was no longer reduced. Thus, the swivel joint 332 is provided to maintain the desired range of angles between the wand nozzle 328 and the surface being washed.
A drawback to the power washer wand disclosed in U.S. Pat. No. 6,158,677 is the expense in producing the loop 330, shown in FIG. 3A. A commercial embodiment of the loop, shown in FIG. 3B, is manufactured in four bending steps. To manufacture the commercial embodiment of the loop shown in FIG. 3A, a single piece of metal, such as ½ inch diameter iron pipe or steel tubing, or other suitable material, is bent into a loop with a mechanical bend of over 180°, such as loop 330 as shown in FIG. 3B, which typically requires four bending steps. A die is typically needed for each bend, and each bend involves a separate bending step. The loop 330, illustrated in FIG. 3B, comprises a first bend 331 which is a 45° bend, a second bend 333, which is a semicircular bend of approximately 190°, and a third bend 335 which is a 45° bend. The first bend 331 is typically produced using one die and one bending step. The second bend 333 is typically produced using one die and two bending steps. Two bending steps are performed because as noted above, a bend of over 180° is difficult to produce. Therefore, a 180° bending step is first performed on the material, and then the material is adjusted and a further bending step is performed in the material resulting in the 190° bend 335. The third bend 335 is produced in the same manner as the first bend, using one die and one bending step. Therefore, a commercial embodiment of the loop 330, as illustrated in FIG. 3B, is produced using two different dies and four different bending steps. The bending steps can be performed, for example, on a Hossfeld Universal® Bender, manufactured by Hossfeld Mfg. Co. of Winona, Minn. Thus, manufacturing a loop 330 as illustrated in FIGS. 3A and 3B, will typically require two different dies and four bending steps. These multiple dies and multiple bending steps increase the manufacturing cost of the wand.
It is therefore an object of the present invention to provide a power washer wand which reduces the back pressure caused by the water stream.
It is a further object of the present invention to provide a power washer which may be used to reach distant surfaces without the use of a scaffold or ladder.
It is yet a further object of the present invention to provide a power washer wand which may have an extended length without any compromise in nozzle pressure.
It is an even further object of the present invention to provide an improved extended wand.
It is still a further object of the present invention to provide a power washer wand which is inexpensive to manufacture.